Cats often have sinister meanings in people's impressions, even some ghosts (I don't have this prejudice against cats, but I prefer cats myself). When they appear behind you, you want to catch them but can't touch them, which probably indicates your fear of some unknown tests. Finally, you catch the cat and find that it is blue, which is not the color that cats will appear in reality. The cat here is probably your imaginary enemy, and you are also afraid of cats. You say.
To sum up, this dream is likely to be that you want to rely on it in the new competitive environment, but there is no hope in the end, so that you hope to destroy your opponents and unknown tests through death.
Of course, since I am not good at interpreting dreams, the above is just a guess based on your dreams. You don't have to be serious. In addition, if you cling to an empty dream, you may be a sensitive person and tend to take things to heart. There is no need to take things so seriously. As long as you have a clear conscience about people and things, dreams are just dreams. There is really no need to care too much.